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Re: Soft-RAID and Hard-RAID?

At 15:55 -0400 04/30/2002, Michael G. Schabert wrote:
At 5:16 PM -0400 4/29/02, Kok-Yong Tan wrote:
While a RAID 5 config may function perfectly well with one drive missing, what do you think will happen if you do so and another drive fails before the RAID system is rebuilt?

the exact same thing that will happen with your RAID 1 if the mirrored drive fails after the primary. You're contrasting RAID1 with RAID5...but BOTH will give you catastrophic, unrecoverable data loss in the instance that you specify.

True. Mr. Gardner said that RAID-5 was more robust than RAID-1. I'm showing him that it isn't from my real-life experience.


Unlikely, you say? Well, it happened to me and, boy, will I not do it again!!! Now, I always work on the worst case scenario, especially when handling data and leave the "cowboying" to other people. Perhaps you've had bad experiences with badly implemented RAID 1 solutions but the systems I manage have complete failover where someone can yank a RAID-1 drive out and it will failover instantly to the mirrored volume with nary a hiccup.

But you said that before we insert a new drive, the second drive fails. In that instance, with your RAID1, you're still hosed. Only extoll the virtues of your system if it does *NOT* have the same limitation that you're complaining about.

No. I said a "second drive fails before the system is rebuilt". The new drive may already be inserted but the RAID hasn't completely rebuilt, just partway done. And the second drive to fail may not be the new one. And as I said, I have experienced a RAID-5 secondary drive failure in exactly this manner. However, I have not experienced a RAID-1 failure as you have described. These are my experiences. Your arguments are theoretical assumptions. Mine are real-world experiences. I'm only talking about my real-world experiences. Period. Perhaps a drive may fail in the manner you describe but I have not experienced it yet. You have a nasty tendency to shoot your mouth off without reading the fine print. And this is not the first time we've exchanged words on that issue.

Of course, all our arguments are moot because they aren't available to MacOS X Server. Oh well. Let's leave it at that.

Sez who? Lots of people are running RAID levels zero, one, and five on OSX(S). They're just not running SOFTWARE versions of L5. But that is said of System 9 as well. Remus was only qualified up to OS8.x.

"Sez who"??? Here we go again. You're claiming that hardware RAID level zero, one and five is available on a single PCI ATA/(E)IDE card for OSX(S) as requested by the original poster? I don't claim to know all manufacturers of PCI-based solo ATA/(E)IDE RAID cards that work on MacOS X Server but you seem to have a handle on this, so which manufacturer is it that has such a proven system? I'm sure inquiring minds would like to know just in case we ever see a request for this in the field.
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References: 
 >Re: Soft-RAID and Hard-RAID? (From: "Jon L. Gardner" <email@hidden>)
 >Re: Soft-RAID and Hard-RAID? (From: Kok-Yong Tan <email@hidden>)
 >Re: Soft-RAID and Hard-RAID? (From: "Michael G. Schabert" <email@hidden>)



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